Dodge master cylinder install help

Sabas · Sep 17, 2017

Installing a master cylinder from dodge ram charger. Using astrovan hydroboost. Installed new brake lines as I did Ford disc brake conversion with t bird calipers. Bleed the system still have soft brakes, thinking I need a slug in master cylinder?
Anyone have this issue.

Sabas

toddz69 · Sep 17, 2017

Check the pushrod to master cylinder clearance - the Astrovan pushrod is pretty short (barely comes out of the end of the booster) and you need a reasonably long pushrod into the back of the Dodge master cylinder. You probably have a ton of clearance between the two.

Todd Z.

Apogee · Sep 17, 2017

toddz69 said:
Check the pushrod to master cylinder clearance - the Astrovan pushrod is pretty short (barely comes out of the end of the booster) and you need a reasonably long pushrod into the back of the Dodge master cylinder. You probably have a ton of clearance between the two.

Todd Z.

X2...GM is either short or long output rod from the booster, Mopar is somewhere in between. I thought I saw a GM/Mopar pushrod spacer the other week somewhere, but can't find it again. I know Hydratech put Mopar specific output rods in their units to run the Mopar MC's, but they don't sell them separately. It's possible that one of the other HB sellers does though.

Otherwise machine something up in the lathe and use clay or putty to check the clearance. You want something like ~.020" clearance between the output rod and MC piston give or take.

ntsqd · Sep 17, 2017

Oddly converting my last year of vacuum booster CTD to the next year's H-B system using all stock replacement parts from Rock Auto still required a plug spacer in the rear of the m/c.

The H-B unit on the Bronc-up looks to employ the adjuster tip from an FE engine's adjustable rocker-arm push-rod to make dialing in the length easy to do.

Sabas · Sep 20, 2017

Got the pushrod swapped out and the shop did it for freeeeee.

Sabas

Pa PITT · Sep 21, 2017

So SABAS DID THE NEW ROD FIX YOUR ISSUES.

Sabas · Sep 21, 2017

I will find out this weekend, but it should. I placed a small bolt last weekend to take up the space and the brakes worked, so that's when I figured I need either to get a longer pushrod.

Sabas

Sabas · Sep 23, 2017

PaPITT, pushrod fixed my issues, I have brakes

Sabas

Sabas · Sep 24, 2017

Just my radar brakes loc up before the front, any thoughts?

Sabas

ntsqd · Sep 24, 2017

You got radar brakes?!?!? That's some trick, late model schiat.......

Prolly either need to adjust it or add and then adjust a proportioning valve. wilwood's got some in combo blocks that might mean less re-plumbing.

Sabas · Sep 24, 2017

ntsqd said:
You got radar brakes?!?!? That's some trick, late model schiat.......

Prolly either need to adjust it or add and then adjust a proportioning valve. wilwood's got some in combo blocks that might mean less re-plumbing.

I have a propotioning valve on it, but it's pretty old, thinking of ordering a new one

Sent from my SM-N950U1 using Tapatalk

ntsqd · Sep 24, 2017

See if dialing out some rear brakes helps any.

Apogee · Sep 26, 2017

X2 what Thom said above.

Are you still running drum brakes in the rear? If so, which ones? What wheel cylinders? If you currently have the 15/16" wheel cylinders, then you could step them down to the 7/8" units to reduce the rear brake bias slightly. You already have the larger T-bird front calipers, so that should already push the bias forward some over the small piston calipers.

What are you running for front pads? Another option is to step up the pad CoF up front to shift the bias forward more, regardless of what you're running out back.

Sabas · Sep 26, 2017

I'm running T-bird disc in front & Explorer rear disc. Running pads that came from BC.

Thanks for input

Sabas

Apogee · Sep 26, 2017

Sometimes with short wheelbase, lifted CoG rigs with soft suspension, there isn't much you can do to prevent rear lockup under all circumstances due to the degree of weight transfer from the rear to the front, at least not without changing your suspension geometry, spring rates, etc.

toddz69 · Sep 26, 2017

Apogee said:
Sometimes with short wheelbase, lifted CoG rigs with soft suspension, there isn't much you can do to prevent rear lockup under all circumstances due to the degree of weight transfer from the rear to the front, at least not without changing your suspension geometry, spring rates, etc.

As part of a project I've been working on recently, I've had an opportunity to go back and re-read a lot of the period road tests of the early trucks (76-77 with discs) and the later model rigs as well. I was reminded how frequently testers complained or mentioned rear brake lockup with fresh factory rigs. Sometimes you just can't beat physics. It was until Ford added rear ABS in '87 that the problem started to disappear.

Todd Z.

ntsqd · Sep 26, 2017

With rigs that are particularly prone to rear lock-up I like the LBS . It doesn't reduce rear braking like a p-valve does, it just delays or slows the pressure rise which allows more weight to move back onto the rear axle before the rear brakes really start to work.

toddz69 · Sep 26, 2017

ntsqd said:
With rigs that are particularly prone to rear lock-up I like the LBS . It doesn't reduce rear braking like a p-valve does, it just delays or slows the pressure rise which allows more weight to move back onto the rear axle before the rear brakes really start to work.

TS:

Do you plan to use one on the Broncup?

Todd Z.

ntsqd · Sep 26, 2017

I've given some thought to ditching the wilwood P-valve and trying one on it. One of them worked extremely well on Rod's IFS 9"/9"'d T-100. First I need to finish the atlas shifter, build the exhaust system, and do the Exploder front dress swap. And quit dicking around with the 4rnnr so that I can get those things done....

Dodge master cylinder install help

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